Revealing mistake: Reapers look 'different' in reflections and recordings, yet sometimes you can catch them with 'normal' reflections, eg. Rube in the diner window.
Revealing mistake: When Mason and George walk up to the TV's in the store, the TV images do not match Mason and George's movements, as it records them.
Chosen answer: The Song is Callled "Boom Boom Ba" and is by the band Metisse. it plays at certain points during the series. Mainly when George is looking over Reggie or in Reaping Havoc where it plays whilst shes showing her scrapbook "Mysterious and Reassuring" which is what she thought Betty was.